Monday, November 24, 2008

The latest iteration of the Green500 list was released at the SC08 supercomputing conference in Austin, Texas. It is the first time high-performance computers have executed more than 500 million floating-point operations/sec (megaflops) for every watt of energy they used, according to the list's compilers.

The most energy-efficient supercomputer is a 2,016-processor machine at the University of Warsaw's Interdisciplinary Centre for Mathematical and Computational Modeling. The system, based on IBM BladeCenter QS22 servers, produced more than 536 megaflops per watt.

That system and the next six systems on the list run IBM's multicore Cell Broadband Engine (Cell/B.E.) processor. Four of those systems use IBM's new QS22 blade server. The top four machines all achieved more than 500 megaflops per watt.

Overall, the participating supercomputers showed a 17 percent increase in energy efficiency since the last edition of the ranking, released in June.

Wu Feng and Kirk Cameron, associate professors at Virginia Tech, started the Green500 in 2006 as a way to encourage supercomputer developers to think more about the amount of energy their creations consume. In the past few years, supercomputer managers have started to notice that the increasing size of their machines brought about a corresponding increase in energy bills.

"For decades now, the notion of performance has been synonymous with speed," the Green500 Web site states. "This particular focus has led to the emergence of supercomputers that consume egregious amounts of electrical power and produce so much heat that extravagant cooling facilities must be constructed to ensure proper operation."

The Green500 list is compiled from the biannual Top500 list of supercomputers, the latest iteration of which was released earlier.

Top500 participants were encouraged to submit data on the average amount of energy their systems used during a Linpack run, a benchmark that determines their rankings on the Top500. Positions on the Green500 are calculated by dividing the Linpack score, measured in flops, by the average amount of wattage used during the testing.

In the latest Green500 compilation, 276 of the top 500 sites submitted their energy usage, a 19.5 percent increase from the number of submissions in June. The list's compilers estimated the rest of the scores.